1. Field of the Invention
The present invention relates to an image recording/reproduction apparatus such as a digital camera or a digital video camera, an index displaying method by an image recording/reproduction apparatus, and a computer program therefor.
2. Related Background Art
In a digital camera for example, as a method of displaying image data recorded in a removable memory such as a memory card, there is known, in addition to an ordinary display method of displaying an image only, an index display method of simultaneously displaying a plurality of small images (thumbnail images) of the recorded image data.
Such index display is a function of simultaneously displaying small images of the image data recorded in the removable memory by (m×n) images (for example 6 images) or by (m×m) images (for example 9 images) for example. In such index display, it is important to display as much information as possible in an easily observable manner within a limited display space such as a liquid crystal panel incorporated in the digital camera or an external monitor (for example television).
Also there is known an image reproduction apparatus which, in response to a selection of a size of the small image to be displayed in an index display, determines a number of displayed images according to a screen (size and aspect ratio) of a monitor to be used for image display (cf. Japanese Patent Application Laid-Open No. H11-212755).
Owing to the high-vision television broadcasting started in earnest recently, television sets of a wider screen with a 16:9 aspect ratio are becoming popular in addition to those of conventional 4:3 aspect ratio. Also the digital cameras and the digital video cameras, capable of recording image data with an aspect ratio of 16:9 in addition to those of a 4:3 aspect ratio are becoming available. Therefore, a removable memory is often found to contain image data of plural aspect ratios in a mixed state.
Image data recorded by current digital cameras are principally JPEG image data of a format conforming with Exif (exchangeable image file format) standard. The Exif standard defines a file format constituted of a header, a thumbnail image part and a main image part, in which the thumbnail image part defines to record therein an image data of an image size of 160×120 pixels (aspect ratio 4:3). An index display on the digital camera is usually executed using such thumbnail image.
However, as to a file recorded with a 16:9 aspect ratio (1920×1080 pixels) of a main image, an index display is given by a thumbnail image of a 4:3 aspect ratio, displayed in a letter-box manner by attaching solid black areas above and below the image of the 16:9 aspect ratio.
Therefore, in an index display on a conventional image reproduction apparatus, an image of a 16:9 aspect ratio is displayed with a 4:3 aspect ratio in a letter-box style, as shown in FIG. 7, mixedly with ordinary images of a 4:3 aspect ratio. Consequently, the image portion of the image of the letter-box style, necessary for the user, is very difficult to recognize, since the image portion is displayed in a reduced form and the image is displayed in a letter-box style in a part thereof.